Towards Ultra-Wide Voltage Window (3.2 V) Aqueous Symmetric Supercapacitors  Triggered by Hybridizing  Fenico Oxides with Ni (Pyrithione)2  On  Feni Foam

Abstract

The low-decomposition-voltage (~1.23 V) of water enormously restricts the workable voltage of aqueous symmetrical supercapacitors ( ASSC s) , which correspondingly limits the energy densities and frustrates the commercialization of ASSCs . Herein, the voltage window of an all-solid-state ASSC can be extended via employing a novel self-supporting hybrid electrode constructed by coupling FeNiCo oxides with Ni (pyrithione) 2 on FeNi foam (denoted as NiPT@FeNiCo oxides/FNF ) as both cathode and anode, which was synthesized using two-step hydrothermal processes. Primarily due to the introduction of redox-active pyrithione ligand chelating Ni ions supplemented by multiple pairs of reversible redox reactions to suppress water splitting, the assembled all-solid-state ASSC device exhibits an extra-wide workable voltage window up to 3.2 V with ultrahigh energy exporting densities (92.7 Wh kg −1 at 246.2 W kg −1 , and 29.2 Wh kg −1 even at an elevated 2461.5 W kg −1 ) . The energy density feature of this assembled all-solid-state ASSC device is superior to most existing transition metal oxide-based supercapacitors and even asymmetric or hybrid devices heretofore reported. After 10000 cycles, this assembled all-solid-state ASSC device records a 90.9% retention of initial area specific capacity. Our work offers a robust combination strategy to design high-potential electrode materials for constructing high-voltage aqueous ASSCs.

Keywords: Ni(pyrithione)2, FeNiCo oxides, FeNi foam, high voltage window, aqueous symmetrical supercapacitors